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Copyright 2004 Native Prairies Association of Texas
Based on work over the last 70 years, it is evident that the prairies in Texas had an incredible diversity of species that supported a vast array of animals. Texas prairies vary widely in species composition. Different topographies, elevations and aspect to sun affects local species composition, as well as micro-relief, such as gilgai or mima mounds or a buffalo wallow. The size of the prairie remnant and its’ past history of use will also have a huge impact on what species survived.
The Big Four prairie grasses (Big Bluestem, Andropogon gerardii; Indian Grass, Sorghastrum nutans; Switchgrass, Panicum virgatum L; Little Bluestem, Schizachyrium scoparium) at one time towered over the prairies of the American plains, with huge seas of waving grass under the sun. The big four species made up 50 to 80 percent of the plant composition that provided a valuable forage reserve for wild herds of buffalo, deer, elk and other wild animals native to North America plains. Today these species can still provide excellent forage for cattle and wildlife.
In selecting which species of grass to plant, it is important to recognize which combination of the big four and other grass species were once dominate in the area that you want to restore. The Tallgrass Grassland Series has been described as four broad arrangements based on specific dominance of the big four, according to David Diamond and Dr. Fred Smeins:
|Series||Plant Associations||Region of Occurrence|
|Little bluestem-Indiangrass||Little bluestem-Indiangrass||Blackland Prairie Alfsols and the San|
|Little bluestem-Indiangrass||Blackland and Fayette||Little bluestem-Indiangrass-Big bluestem|
|Little bluestem-Indiangrass||Little bluestem-Big bluestem-Indiangrass||Blackland Prairie Mollisols and the Fort|
|Little bluestem-Brownseed Paspalum||Little bluestem-Brownseed Paspalum-Indiangrass||Fayette Prairie Alfisola and the Upper Coasta|
|Gamagrass-Switchgrass||Gamagrass-Switchgrass-Indiangrass||Northern Blackland Vertisols and Iowlands|
|Silveanus Dropsed||Silveanus Dropsed-Mead Sedge||Northern Blackland|
At the time of European settlement, the plains area of North America gave way to the plow and a large percentage of the Tall Grass prairies were destroyed. There is a need to re-establish these species and preserve the heritage of the Tall Grass prairie that nature provided us in the beginning.
The big four prairie grasses grow in a variety of soils including those of shallow depth, low pH and low fertility. In low pH soils (5.5 and lower), the addition of lime will be necessary. Other species need to be included in a native grass planting in order to maximize diversity. Additional grasses may include eastern gamma grass, sideoats gramma, tall dropseed, Texas cupgrass, Texas wintergrass, brownseed paspalum, fimbry, purple three-awn, Canada wildrye, Florida paspalum, microdentate sedge, Carolina jointtail, Mead sedge, Silveanus dropseed, tridens sps. Among the forbs, the following were found to be dominant in little bluestem-Indiangrass remnant prairies: false dragonhead, old plainsman, prairie acacias, bishops and bluets as well as prairie coneflower. Among the Little bluestem-Brownseed Paspalum remnants, button snakeroot and compass plants were dominants, as well as heath and silky asters, Indian plantains, meadow pinks, sensitive briars and Ruellia sps. In wetter areas, brown-eyed susans, Maxmilian sunflowers along with the aforementioned acacias, bishops, coneflowers and sensitive briars, as well as camphorweed are prevalent. In the northern Silveanus Dropseed-Mead Sedge associations, brown-eyed susans, cudweed, flax sensitive-briar, silky aster and yellow-puffs are common.
Ultimately, the species that will dominate in a given area will depend on management, soil characteristics and climatic conditions. Do not limit yourself to the listed species above, though - use them as a guideline. Find any remnant prairies in your area and determine the species composition. It is important to know its past management history, i.e. how often and how intense has it been grazed or hayed? Has it been sprayed with broad-leaf herbicides? Remember to include appropriate legumes, such as plants of the genera Desmanthus, Baptisia, Cassia, Dalea, Astragulus and Psoralea. These will add fertility to the soils over time.
The main point is diversity. The more species, the more resilient the prairie to drought and other catastrophes, and the more it can support a greater variety and number of birds, mammals, insects and reptiles, not to mention the aesthetic appeal to the human.
The big four grass species and attending forb species can be established within variety of situations using a range of planting techniques. To get good stands, seeds should be placed in contact with the soil surface and where the soil will remain moist during germination and seedling development. Good seed-soil contact is critical.
The following is a list of planting methods, techniques, and guidelines:
|Planting Method||Planting Technique||Planting Guidelines|
|Broadcast||Fertilizer spreader||Mix with disperser, good for large acreage where cattle rotational graze at high stock densities|
|Air seeder||Same as above|
|Chaffy seed spreader||Good for small acreage, difficult to calibrate|
|Hand broadcast||Good for small acreage|
|Hydro-seeder||Uses a hay mulch and water as carrier to blow seed on soil surface. Good for soil erosion control|
|Seedballs||Good for small to medium acreage or where rocky soil precludes the use of seeding equipment.|
|Seed hay||Good method of obtaining local genotypes / ecotypes|
|Drilling chaffy seed||Chaffy seed drill||There are several drills on the market designed to meter. Drills can be rented from an National Resource Conservation Service (NRCS) district. Good for large acreage.|
|Grain drill||Must mix seed with fertilizer. Not good for grain box if used on large acreage|
|Live plants||Planted by hand||Plants are started from seed, placed in pots, and grown in the green house. This method is very labor intensive, and best suited to small areas.|
|Bare roots||Planted by hand||Roots are taken from live plants, placed in a prepared seedbed and watered in. Very high survival rate. Well suiteds mall garden landscapes|
Planting mixtures typically range from 8 to 20 pounds of pure live seed per acre. Due to seed costs, low input planting methods must be considered for large acreage. Suggested pure live seed planting rates are:
• Big bluestem 3 to 7 lbs. per acre
• Indian grass 3 to 6 lbs. per acre
• Switchgrass ½ to 1 lbs. per acre
• Little bluestem 3 to 6 lbs. per acre
• Wildflower Mix 10 to 20 lbs. per acre
Preparing a seedbed is the most assured method of high establishment rates. The seedbed at planting time should be firm and free of vegetation. Seedbed preparation can require several trips over the ground with a plowing disk, a drag to smooth the seedbed and lastly a roller packer to firm the seedbed just before planting. If the seed is broadcast planted a second trip with the roller packer will be necessary to cover the seed (¼ to ½ inch in soil depth) and to insure good seed/soil contact. Old fertilizer spreaders are very effective when broadcasting over larger areas. If the seed is drilled, some types of drill seeders have packer wheel attachments that will press the seed into the soil surface, giving it good seed soil contact. There are also drills especially designed for planting native grass seeds. These are equipped to meter out chaffed, low, and bulk density seed.
If a general-purpose drill like what is normally used to plant small grains or if the seed is broadcast planted, it will be necessary to mix the seed with a carrier or a disperser, such as a dry sand or a extremely low-Nitrogen fertilizer blend (0-20-10 or 6-46-0) to flow the seed through the drill box.
Normally, 1 pound of bulk seed will require 5 to 8 pounds of fertilizer. Avoid using a medium to high nitrogen fertilizer since this will promote competition from exotic, invasive weedy plants and suppress the establishment of beneficial bacteria. Phosphorus and potassium are beneficial in promoting root growth and quick establishment.
If drilling into soils that have been previously abused with chemicals, or extremely overgrazed, soil fauna may be dead or the soil-food-web out of balance. In healthy prairies, organic matter content may exceed 3.5 % - up to 4.8%. The soil fauna will be aerobic-bacteria dominated, but still have a healthy complement of fungi, particularly Mychorrizae fungi that form a mutually beneficial relationship with a plant’s roots. A good way to inoculate your seed prior to broadcasting or drilling is to mix the seed with an equal amount of 1/8”-screened and dried compost. The compost quality is critical. It should have been heated properly and remained aerobic in the process and allowed to sit for a month or so after the final cool-down. Actinomycetes bacteria and Mychorrizae fungi may be added for the final cool-down phase. After allowing the seed-compost mix to sit overnight, mix with dry sand or fertilizer to help the chaffy seed flow through the equipment. See http://www.soilfoodweb.com/.
When using a native grass drill, otherwise known as a rangeland drill, there are some tips to follow to help insure success and one basic thought to keep in mind; chaffy native grass seed does not behave like smooth-coated seeds, which flow much easier. Although rangeland drills are designed to plant chaffy native grasses, the “fuzz” and appendages of these seeds tend to stick and adhere to everything.
Do not plant too fast. The first impulse after the drill is set and calibrated is to get done as fast as possible. Planting should be done at 3 to 5 MPH. The fluffier the seed, the slower you go, and the more inert material in the seed, the slower you need to go. Several problems occur if you go too fast. Seed falling from the drop tube to the furrow hits the spinning coulter. Native grass seed, being light and fluffy, is sent for a ride, perhaps falling in furrow, perhaps not. It is often the case where more seed falls outside the furrow rather than in, resulting in a thin and scattered stand of seedlings.
• Drilling too fast also bounces and packs the seed. In the worst possible case scenario, seed will pack so tightly that it ends up shearing a pin.
• Check the planting depth. Drill forward 10 to 15 feet and check the planting depth. Make any adjustments and repeat the procedure if necessary. Remember, seed deeper than 1/2 inch will most probably be lost. Some seed on the surface is acceptable, actually preferable to being too deep.
• Take the tractor up to planting speed and plant a few hundred feet. Stop, and then check the planting depth again. Seed placement will be different under actual planting conditions than at slow speeds and short pulls. The bouncing of the drill and the faster turning furrow openers will have an affect on planting depth. It is important to check planting depth under actual planting conditions.
• Fill the seed boxes loosely, level to the top. Do not pack seed into the box to get that last little bit left in the bag. Packed seed will not flow through the drill the same, if at all, and calibration will not be accurate. You may also run the risk of packing seed so tight that it will shear a pin.
• Check the level of seed in the seed box often. You don’t want to waste your time pulling an empty drill. Stopping and checking also serves as a means to recheck calibration. Once you are calibrated you should be able to keep track of the time and get an idea of when you need to stop and refill. The drill holds X number of bags of seed, one bag plants Y acres and you are planting at a rate of Z acres an hour.
• Keep the seed level above the agitator shaft. Drilling with less seed will result in inaccurate seeding rates.
• During drilling, when the soil is too wet, the seed between the furrow openers will stick to the soil as it is pulled out of the ground as the coulters pull through and out of the soil. Some of the seed ends up on top of the ground but most of it ends up stuck to the out side of the coulters with all the mud.
• One of the most common mistakes people make when drilling chaffy seeds is once the drill is calibrated and set, off they go never looking back to check the drill. An hour later when they stop to refill the seed box, lo and behold, one or more dividers in the seed box is still full. A clogged drop tube is usually the culprit.
A good rangeland drill will have a means to visually check to be sure seed is flowing from the seed box through the drop tubes into the furrow openers. Any chaffy seed you buy will have some small plant stems or other debris, which could clog the drop tube. If you regularly check the openings in the transitions, you will know immediately if a drop tube is plugged. Stop the tractor and drill and unplug it. Many are tempted to just ignore it and go on, particularly if it is just one-drop tube. Resist the temptation, as time goes on the clog will only get worse and can become a nightmare to relieve.
While looking back and checking, be sure to see that everything is working properly. Sheared pins, chains off of sprockets, clutches engaged or any number of things could be happening (or not happening) to keep your drill from working. The worst thing you can do is spend several hours planting to discover you haven’t planted a thing.
Check and recheck calibration. When calibrating, put enough seed into the seed box to at least cover the auger shaft. If you use less seed the calibration may be inaccurate. Repeat the calibration procedure several times to confirm your results. Non-flowing native grasses do strange things. Check at least 3 times after you think it is set. If you get similar results two of the three times then consider it set but don’t forget about it. Ground check your calibration. You know that a 50 pound bag of seed will cover X number of acres. Put in one bag, estimate X number of acres and check to see if you are still on track.
Chaffy seed flows through a drill differently depending upon the roughness of the terrain, planting speed and even humidity. Calibration always needs to be checked under actual planting conditions and rechecked throughout the day. Humidity has a surprising affect on fluffy seeds. The drier the air, the fluffier the seed. This is noticeable with little bluestem. If you are planting over two or more days recheck the calibration each day. Recalibrate when you change lots of seed, even if they happen to be the same PLS. Different lots flow differently.
Hydro seeding, often called hydro mulching can be a successful method of broadcasting native grasses and wildflower seed, but only if the mulch particles are large and the consistency of the sprayed mix is quite liquid. Since ‘fuzzy’ seed tends to suspend in high-density, pulpy mulch, the seed doesn’t actually make good soil contact, thus, lowering the amount of germination and establishment. However, large particles mulch can enhance establishment by retaining moisture in the soil. Rain will wash the native seed around the largish stems and make adequate soil contact.
Seed hay is simple hay cut from a prairie remnant. It contains a broad range of grasses and forbs desired. Seed hay is a method of taking advantage of existing technology to gather desirable grass and forb seed and mulch, along with a complement of wildflower seed. This method also diminishes any selective criteria on the available genetic variance in a given locale. The trick is to diminish the seed loss between the time the hay is cut and baled. If cut too early, a lot of the seed will not have set. If cut too late, much seed will be lost as the stems dry prior to baling. The cutter must not crimp the stems as they pass through the machine. This will also cause much seed to shatter. Also, the cut hay must not be raked too much, as this too will shatter much seed. However, the hay must be totally dry prior to baling, otherwise the moisture will start the bale to compost as it sits rolled up. As the internal bale temperature reaches 140oF, the seed will ‘cook’ and be useless. So be careful, timing, technique and attention is everything.
Successful plantings are made into standing vegetation. Seeds are broadcast planted in early spring and then treaded or trampled into the soil with a high density of grazing animals. Bison are ideal, but livestock (cattle, sheep, goats, and horses) will suffice. Animal hoof action will stir the soil and at the same time press the seed giving good seed soil contact. Good hoof action will require herd densities of 8 to 10 animals per acre for a given period. Also grazing at a high density of animals will help control weedy plants. Numerous successful plantings have been done using this technique.
Burn-down herbicides will stop the growth of all vegetation. This practice is beneficial just before broadcast planting into existing weedy vegetation. Using an herbicide will make it illegal to harvest hay or graze for an extended period. In small areas, black plastic is also very effective in killing weeds and their seed. The soil must be very wet prior to placing the plastic down to be effective. The closer the plastic is to the ground, the better this method works. In effect, the seed and plants at the soil surface are “steamed”. Allow the plastic to remain in place for six weeks during the heat of summer.
Getting stands established in low rainfall areas can be a problem, There is not enough cover to protect the soil from wind erosion and hold the necessary surface moisture for good germination and seedling survival. A common practice to overcome this problem is to grow an annual crop of Sudan, millet wheat or cereal rye on a prepared seedbed the year before. This is called a stubble crop or dead litter crop. Then let plant residue accumulate on the soil surface at the end of the growing season. Combining, haying or partial grazing can control the amount of residue. At frost time, you would want the soil to cover with enough litter to prevent winter weeds from growing. In early spring, broadcast seed over the litter. Rainfall will wash the seed beneath the litter. Or drill between the stubble rows.
Seedballs were first invented by Masanobu Fukuoka in Japan after WWII. Popularized by Jim Bones in the late 1990’s, seedballs have proven to be an effective technique in areas that are too large to use hand equipment (rakes, etc.) and too small for tractor equipment, such as drills, etc. They have also proven to be successful on slopped or rocky areas that are common in the Texas Hill Country. Or when inter-seeding new species into prior planted areas. The clay pellet, approximately 3/8” to ½” in diameter should contain all the complement of species you want to broadcast on the restoration site. Compost and any other amendments can be added prior to rolling. A typical recipe calls for the following:
• Seed: 1-2 parts
• Compost: 2-3 parts
• Sand ½-1 parts
• Clay: 4-6 parts
• Water: Very little, as needed.
Mix seed and compost well, to inoculate the seed with the beneficial bacteria in the compost. Then add sand, amendments, and clay. Mix well again. Add a little water at a time, while mixing the vat. The final consistency should be that of peanut butter. Pinch off small amounts and roll into balls in the palms of your hands, until you feel it get hard. Throw the seedball on to a tarp or raised screen to dry. Only mix-up an amount that you will finish rolling within an hour or two. Keep working a little at a time. Once the seedballs are dry, throw out by hand at the restoration site. The clay will protect the precious seed until rain arrives, then the seedball will melt and the seed will germinate. The clay will also keep the seed in place if the rain turns into a ‘gully-washer’.
To step-up production beyond hand rolling, try the “Van-Bachmeyer” drum, which is a 55 gal. drum, laying horizontal on a portable stand, which is driven by an electric or gasoline motor. This method is capable of producing up to 110-150 lbs. per day. Of seedballs per day, enough to cover an acre at a rate of 1 seedball per square foot, or 10-20 lbs. PLS seed/ac.
Higher production rates may be accomplished using a “pan-roller”, which is an industrial grade piece of equipment designed to handle ore for the mining trades.
As in any other planting, make sure to suppress the weeds and/or eradicate the exotic invasive species prior to broadcasting the seedballs.
Other planting techniques may involve transplanting plugs of live plants. This method is very successful, particularly when salvaging plants from development sites, but labor intensive and not economical on large areas. Plugs are commonly used for small plot areas of a 1000 sq. ft or less to establish a prairie garden or eroded sites where it is difficult to get stands. Seed companies will also take nodes of live plants placed in containers, start plants growing in a green house for transplanting. Plants should be spaced at 18 to 20 inches apart with soil firmly packed and watered in.
It is important to take a soil test before planting any seed. Look at micro (or trace elements) as well as the macro elements (NPK). Proper and available Calcium amounts and the Ca: Mg. ratio is critical for proper cell wall growth and health. Make sure the elements are determined using water and carbon dioxide, as opposed to strong acids. As the former method will tell you what your plants are more likely to actually “see”. Plant tissue samples are also beneficial if possible. This will tell you if the desirable plants can actually make use of the elements that are present in the soil. Cation Exchange rates and soluble salts as well as total organic matter content are useful parameters as well. At the very minimum, soils that test low in phosphorus, potassium, and calcium need to be amended with these elements. Native grasses can grow in low nutrient soil but these conditions will affect the overall growth and plant health. Research has shown that plants will respond to phosphorus for plant establishment. Phosphorus will also aid a plant is root development and boron, only needed in very trace amounts, helps seed-set in native grasses.
Native grasses will not respond to nitrogen fertilization. Nitrate nitrogen can be a detriment in getting good stands in that it will promote competition from weeds and other undesirable plants. Excessive nitrate nitrogen can effect soil microbes and limit the development of the proper food web for Native grass plants to grow.
A microbe or soil faunal assay is also very helpful in determining the health of your soil. This is because, bacteria in particular, are the temporary holders of available nitrogen in the system, that when eaten by protozoa, becomes immediately available to the plant roots. Otherwise, the nitrogen, as is very mobile, would be washed out of the soil and end up in creeks and rivers after each rain event. The assay will also tell you if root-eating nematodes have reached critical levels. The “take-home” message here is if you properly feed your soil, and grow healthy populations of beneficial microbes, they will grow the desirable native prairie plants for you.
Weeds are those low successional plants that tend to dominate in prepared seedbeds, often of Eurasian origin. They must be controlled or suppressed until native plants are well established. Control methods may consist of mowing, grazing, hoeing or the use of selective herbicides. It is recommended that particularly invasive species such as Johnsongrass (Sorghum halapense), KR bluestem (Bothriochloa ischaemum), and Bermuda grass (Cynodon dactylon) be completely eliminated before restoration attempts are started.
Seedling grass plants do not get very large the first year. Mowing at 4 to 6 inches in plant height will help hold back weedy plants. You may need to mow several times over the course of the growing season. Avoid any mowing in the fall as grass plants may be getting enough height that the mower could affect them. Plants need to make necessary top growth in the fall in order to store root reserves for winter survival.
If weeds have completely overgrown your new seedlings before you’ve gotten a chance to mow, it may be better to not mow at all. The foremost concern, particularly a problem with rotary mowers, is the accumulation of litter in windrows. The thick mat of dead vegetation caused by a rotary mower will choke out and kill any new seedlings eliminating any chance of establishment, whereas the new seedlings stand somewhat of a chance without mowing. As long as they are alive, they at least have a chance of making it. Native grasses also, under heavy, tall weed pressure, respond by growing as tall as necessary to compete, thereby being susceptible to clipping when the weeds are mowed. A good example is when foxtail becomes a problem and grows 3 feet or taller, native grass seedlings, though very spindly will grow 18 inches to 2 feet tall with all leaf area above 18 inches. When mowed at 12 inches a sequence of negative reactions begin. Because of their tall spindly growth their leaves get clipped off leaving nothing but the stem causing the plant to pull growth energy from the roots that haven’t had a chance to store any carbohydrates yet, weakening the plant, further reducing it’s chance of survival. I’ve also seen new seedlings, exposed by a recent mowing scalded by the hot August sun, killing them.
Herbicides can be effective in some cases. When planting grasses exclusively, a broad-leaved herbicide such as 2,4-D can be used to control weeds. The problem is that most broadleaf herbicides do not carry a label for use on native grasses. In that case the user assumes all risks. Consult with your local Ag-chem dealer for recommendation of rates and chemical control methods. Also licensing by Texas Department of agriculture may be necessary.
Mowing may not be applicable or economically feasible on a large acreage. Grazing at a high stock density to flash graze an area will suppress weedy plants. Most weeds are palatable to grazing livestock when they are small and succulent in early spring. Weeds have shallow root systems and can be overcome with grazing pressure. Sheep and goats prefer weeds over grasses and will selective graze them. An additional benefit to flash grazing is that the high concentration of animals for a short while will consequently cause a nice, concentrated odor plum that dung beetles will smell for miles and come flying in. Research has shown that dung beetles can bury over a ton of manure per acre per day. Not only does this fertilize and increase the productivity of the soil, by feeding the microbes with organic matter, but it circumvents the blow-fly life-cycle that can transmit animal disease. Increased aeration and water-holding capacity also occurs as a by-product, that in turn helps the health and productivity of the native plant community.
It will take 2 to 3 years for native grass plants to become established. After they become mature and produce seed, plants will require very little maintenance. It is best if they are rotationally grazed. Grass plants by nature are meant to be bitten and harvested by grazing animals. Grazing will force plants to produce lateral shoots creating new plants. If left un-grazed, the accumulation of residue in time will began to smoother and choke plants limiting their survival and capping will prevent, and preventing new plants from germinating. Rotationally grazing is the best method to prevent the accumulation of residue. Plants respond to rest between grazing periods. Plant material is cycled through the animals and returned to the soil as organic matter. Dung beetles will move in and do what they do best.
Mowing and controlled fire are methods of removing old prairie thatch. In natural prairie ecosystems, fire not only gets rid of accumulated thatch, it also helps reduce woody plant invasion and stimulates the growth of many native grasses and wildflowers. Timing of burns and the choice of a cool burn versus a hot burn will have different effects on species composition. Historically, burns occurred with frequent regularity in Texas, usually in the summer time. Keep in mind that a controlled burn is not only a useful maintenance tool, but also a necessary tool since the prairie plant community evolved under a periodic fire and grazing regime. To remove or suppress the presence of fire and grazing is tantamount to hindering the very forces that make prairies what they are. Please be advised that conducting a safe controlled burn requires some expertise and planning. Be certain to check local regulations and permit procedures. When burning, plan well in advance, have all the necessary equipment, have adequate assistance, and always use caution. But do it.